Cetiosaurus oxoniensis is — finally! — the type species of Cetiosaurus

April 23, 2014

We all remember Upchurch and Martin’s (2002) description of the Rutland Cetiosaurus, which remains by some distance the best British sauropod specimen in the literature; and the same authors’ (2003) survey of the genus Cetiosaurus. They concluded that nearly all of its many named species are either nomen dubia or misassigned, and that only C. oxoniensis is a valid, diagnosable species.

(Some of) the Cetiosaurus oxoniensis holotype material, on display in the public gallery of the Oxford University Museum of Natural History (OUMNH)

(Some of) the Cetiosaurus oxoniensis holotype material, on display in the public gallery of the Oxford University Museum of Natural History (OUMNH). From left to right: right femur in posterior view, scapula, right humerus in anterior view, tibia and fibula (designations by eyeballing). Above the long bones, some caudal vertebrae.

Accordingly, Upchurch and Martin informally used C. oxoniensis as the type specimen in their descriptive work, noting that this usage should be formalised by a petition to the International Commission on Zoological Nomenclature (ICZN).

Six years layer, we submitted that petition to the Bulletin of Zoological Nomenclature; a few months after its publication, positive comments from Paul Barrett and Pete Galton followed.

That was in 2009. Five years of silence followed, as the Commission meditated on our five-page petition. (That’s two pages plus front-matter and references). Today, finally, the results are in! The abstract says it all:

The Commission has conserved the usage of the generic name Cetiosaurus Owen, 1841 by designating Cetiosaurus oxoniensis Phillips, 1871 as the type species of Cetiosaurus in place of Cetiosaurus medius Owen, 1842.

So Cetiosaurus finally has a decent type species! Two cheers for the Commission!

I’d always assumed that ratifying the petition would be a no-brainer once the Commission got around to examining it. In fact, their report makes it clear that’s not how it was at all. 16 members voted for the proposal, eight voted against and two abstained. So I guess we were only three switched votes away from having the proposal rejected. Which would frankly have been stupid: every sauropod worker would just have carried right on using C. oxoniensis as though it were the type species anyway.

Why would anyone vote against, you ask? I asked myself the same question. Happily, the decision explains the objections in detail. They nearly all seem to come down to complaints that we didn’t clearly enough explain why C. medius was the previous type species. There’s a reason for that: the truth is that the literature is so vague and contradictory that no-one really knew what the heck the type species was — which is one of the reasons we needed to establish one. (Upchurch and Martin 2002:1053 thought C. brevis was the type; as we investigated this in more detail for the petition, we concluded that the claim of C. medius was stronger. But still very weak.)

But all of that seems like pointless pithering to me. Who cares what the type species was? The point of the petition is to establish what it is, and only one Commission member expressed any reservations about the case we’d made — which is basically that C. oxoniensis is what’s always used in comparisons.

Anyway, dissenting opinions notwithstanding, the genus Cetiosaurus now stands before us having been made an honest woman at long last.


The Rutland cetiosaur, reconstruction by Mark Evans (Naish and Martill 2007: fig 3)

… all of which leaves us with the question of what the Rutland cetiosaur is. It’s been assumed to be Cetiosaurus all along, and that identification has to stand until someone publishes a case to the contrary. But there do seem to be persistent rumours that someone somewhere thinks it’s something different. I wonder if anything will ever come of it?



13 Responses to “Cetiosaurus oxoniensis is — finally! — the type species of Cetiosaurus

  1. neotype. not holotype. I got told off by certain quarters for mixing that up once.

  2. Mike Taylor Says:

    I don’t think so. Those bones have always been the holotype of the species Cetiosaurus oxoniensis — nothing’s changed there. All that’s changed is what species is the type of the genus Cetiosaurus.

  3. oh, my bad! I misunderstood.

  4. Mickey Mortimer Says:

    Well, oxoniensis is now the type species regardless of what I write, but let me play Devil’s advocate here.

    You ask “Why would anyone vote against?” Top reason- Owen named Cetiosaurus based on medius in 1842 long before the oxoniensis type was found in 1868. medius seems to be a titanosaur/somphospondylan, whereas oxoniensis is a non-neosauropod. So Owen’s animal was different but had its identity transmogrified long after his death.

    Imagine this happens to one of your taxa. Say in 2033 researchers find a partial skeleton they think shares characters with Xenoposeidon and name it a new species of that genus. For decades people use that specimen as the Xenoposeidon exemplar, but then it turns out the specimens aren’t that closely related. Somehow the ICZN still exists (the Phylocode is scheduled to be published on January 1st, 207N), and the relatively unrelated specimen found in the 2020s is now the holotype of Xenoposeidon. How is that fair? How is that representative of your concept of the taxon? It’s basically excusing laziness and/or incorrect reasoning with nomenclature.

    It wouldn’t be so bad if all cases were like Cetiosaurus, but this has become such a shortcut in dinosaur taxonomy that I’m disturbed. The species taxonomy of Allosaurus hasn’t been examined recently (with Chure’s 2000 thesis being a necessary starting point), but Paul and Carpenter (2010) already petitioned the ICZN to make USNM 4734 the neotype of A. fragilis. Stegosaurus’ holotype has never been described in depth, but after a superficial review of synapomorphies proposed by one paper (Galton, 2010 reviewing Maidment et al., 2008), it was petitioned by Galton (2011) to have stenops be the type species. Not even a chance to have other stegosaur workers disagree. Most recently, Galton (2012) petitioned the ICZN to make trossingensis the holotype of Plateosaurus, because the specimen is an incomplete skeleton vs. a skull (for longiceps) and the type quarry is still open. Why pretend we have a principle of priority when it’s a principle of completeness?

  5. Mike Taylor Says:

    “Fair”? Who said anything about fair? The goal here is “sense and stability in nomenclature” as per the ICZN’s motto. That’s best served by reifying what’s already the universal usage of the name “Cetiosaurus“, not by being fair to Owen.

    Same thing in my case. If some other animal gets universally adopted as what people mean by “Xenoposeidon“, that’s unfortunate; but once it’s happened, it’s pointless having the ICZN keep insisting that it hasn’t.

  6. Mickey Mortimer Says:

    First, I erred in saying medius was a titanosaur. I was thinking of brevis.

    Part of my problem with the Cetiosaurus case is that its authors could have decided otherwise and not led to much taxonomic disturbance. Sure Cetiosaurus was historically important, but between Huene’s era and 2002 it wasn’t that relevant to sauropod studies. It was the Megalosaurus of sauropods- not studied recently, a wastebasket taxon, with no obvious described autapomorphies, thought to have a vague place in cladograms but not included in most phylogenetic analyses. So when Upchurch and Martin (2002, 2003) restudied it, they could have said C. medius was trash and thus oxoniensis gets a new genus. Then we’d have two big papers on this new genus, it would have been included in all the new analyses, and things would have been fine. Just like how most theropod workers were fine in the 90s using Spinosauroidea and Torvosauridae when they thought Megalosaurus was trash. But instead they recommend using oxoniensis as the type species and say they plan to petition the ICZN, so of course everyone follows their lead. And by the time they petition the ICZN in 2009, it would indeed be problematic to associate Cetiosaurus with medius instead (note half of the references to oxoniensis being used are from after 2002). So basically Upchurch and Martin caused much of the problem their petition then fixes and encouraged the creation of much of the evidence supporting their position (e.g. “no other generic name has ever been proposed for C. oxoniensis; nor has it ever been referred to as ‘Cetiosaurus’ oxoniensis.”). This seems off to me, though we’re stuck with Cetiosaurus oxoniensis now.

  7. Mark Robinson Says:

    I wonder if anything will ever come of it?

    Oh goodie, a new ‘pod. When do you think you’ll have the paper finished, Mike?!

  8. Mike Taylor Says:

    Mark — just to be clear, I have no plans to reassess the Rutland sauropod, because (A) I already have a big backlog of descriptive work, and (B) the people to do it would be Paul and John, who know that animal inside-out.

    Mickey, I think you’re way off base in this one. You rightly note that some of the papers we cite as using the name Cetiosaurus to refer to C. oxoniensis come after the Upchurch-and-Martin papers of 2002/2003; but even if you ignore those you have to consider the prior art established by Owen,1875; Hatcher, 1903; Huene, 1904, 1927; Fraas, 1908; Janensch, 1914, 1929; Matthew, 1915; Coombs, 1975; Wild, 1978; Bonaparte, 1986, 1999; Martin, 1987; Upchurch, 1998; and Casanovas et al., 2001. Plus whichever other papers we missed.

    It seems clear to me (which of course is why we wrote the petition, and why Paul and John took the actions they did in 2002) that the meaning of the name Cetiosaurus was already well established; and, crucially, it was unanimously established. No-one was using it in any other way.

  9. Mickey Mortimer Says:

    I don’t dispute that the concept of Cetiosaurus was primarily based on oxoniensis by 2002, only that it wouldn’t have mattered much at that time if Upchurch and Martin went against this, and that they greatly stacked things in their favor by 2009 based on what they did in 2002 and 2003.

    No one used Cetiosaurus as medius instead of oxoniensis prior to 2002 because Upchurch and Martin were the first to examine the species in a modern context and thus figure out they don’t share apomorphies within Sauropoda. Only once this was established could anybody even conceive of disagreeing, but now they would have to go against the people actually working on the taxon, two major descriptive papers on it, and an IZCN petition they knew was coming.

    Here’s a question I’d be interested in learning the answer to- When was the last time a Mesozoic dinosaur’s ICZN petition was rejected? I can think of Coelophysis, Cetiosauriscus, Archaeopteryx, Iguanodon, and now Cetiosaurus. All passed. So if someone reputable declares they’re going to petition the ICZN, is it realistic to oppose them? The answer could be depressing given the recent petitions for Allosaurus, Anchisaurus, Plateosaurus and Stegosaurus.

  10. Mike Taylor Says:

    I don’t dispute that the concept of Cetiosaurus was primarily based on oxoniensis by 2002, only that it wouldn’t have mattered much at that time if Upchurch and Martin went against this.

    Once more I refer you to the ICZN motto: “Standards, sense and stability for animal names”.

  11. Mark Robinson Says:

    Thanks for clarifying, Mike. Hopefully Paul and John have it on their “To do” list.

  12. Mike Taylor Says:

    My guess is that they don’t: they did a fine job of describing the Rutland specimen 13 years ago, and didn’t see anything then that made them think it’s not Cetiosaurus. If someone else thinks it’s not, then it’s for them to make a case, which Paul and John can respond to if they wish. Until someone steps up, it’s just chatter — I probably shouldn’t have mentioned it :-)

  13. […] ICZN petition, and I’m not sure anyone wants to do that. The process is technical, picky and prolonged, and its outcome is subject to the whim of the committee. It’s quite possible someone might […]

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